Sharpening device for rotary knives



Oct. 22, 1968 L. A. BETTCHER SHARPENING DEVICE FOR ROTARY KNIVES 5 Sheets-Sheet 1 Filed Dec. 13, 1965 INVENTOR.

LOUIS A. BETTCHER BY g%j WWW ATTORNEYS Oct. 22, 1968 L. A. BETTCHER SHARPENING DEVICE FOR ROTARY KNIVES 3 Sheets-Sheet 2 Filed Dec. 13, 1965 LOUIS A. .BETTCHER j ATTORNEYQ Oct. 22, 1968 L. A. BETTCHER SHARPENING DEVICE FOR ROTARY KNIVES Filed Dec. 15, 1965 3 heets-Sheet 3 7 W v a FIG.5

INVENTOR.

LOUIS A. BETTCHER ATTORNEYS United States Patent ABSTRACT OFTHE DISCLOSURE A sharpener for an annular blade of a rotary knife,

including a knife holder and a grinding wheel on a common base, the grinding wheel and knife holder being relatively movable to sharpen the annular blade'while the blade is rotated. The knifeholder includes'a dressing tool Selectively movable'to a wheel dressing position.

The present invention relates to knife sharpening devices.

The principal object of the present invention is the provision of a new and improved device for quickly and accurately grinding the blade of a rotary knife having a cylindrical-like blade to sharpen the cutting edge thereof without removing the blade from the knife assembly. More specifically, the invention provides a portable base on which a knife holding means and a motor driven rotatable grinding wheel means are supported for reciprocable movements along intersecting lines so that a knife in the knife holding means can be accurately positioned relative to the grinder wheel and the grinding wheel reciprocated relative to the knife blade. In a preferred form of the invention, the knife holding means includes a grinding wheel dressing tool which can conveniently be positioned for dressing the grinding wheel while reciprocating the wheel in the same manner as when the Wheel is reciprocated for grinding a knife blade.

Other objects and advantages of the invention will be apparent from the following description of a preferred em'bodiment'thereof, reference being made to the accompanyingdrawings wherein: FIG. 1 is a perspective view of a device embodying the invention for sharpening a rotary, annular or cylindricallike knife blade of a knife shown'in dot-dash lines;

FIG. 2 is a plan view of the sharpening device shown in FIG. 1, with the grinding Wheel dressing tool shown'in position to dress'the grinding wheel; V

FIG. 3 is a sectional view taken substantially along line 33 of FIG. 2, with the grinding wheel dressing tool' in the'position shown in FIG. 1; I i l FIG. 4 is a bottom view of the sharpening device with the supporting pads therefor removed; FIG. 5 is a fragmentary sectional view taken substantilally along line 55 of FIGJZjan'd FIG. 6 is a fragmentarysectional view takenfs ubstantially along'line 6'6 of FIG. 2. Referring to the drawings, a knife sharpeningdevice lfl is shown which is adapted to sharpen an annular rotary blade, such as the blade B of aknife K shown in phantom, which 'knife is like that''di's' closed 'in U.'SL 'Patei'it No. "2,827,657. It should be understood, however, that the device could be employed for sharpening blades of similar knives. The blade of the knife K, by Way of example, is annular or ring-like in form havinga generally cylindrical inner surface and an outer beveled surface which forms a cutting edge at the juncture of the inner and outer sur- "faces. The bladeis'supported by a ring-like blade-supporting and driving structure R'atone end of a handle.

The sharpening device 10 comprises 'a portable base structure 11 having a knife holding means 12 and a blade grinding -means 13 suppo r ted thereon forreciprocation I a cutting edge on a knife blade.

3,406,486 Patented Oct. 22, 1968 along intersecting paths so that theannular blade of the knife can be positioned relative to a grinder Wheel 14' of the grinding means 13 and the grinding means reciprocated to move the grinder wheel across an outer surface such as the beveled surface of the knife blade to grind a fine cutting edge on the blade. The knife holding means 12 includes a support structure for a grinding wheel dressing tool 15 which can be conveniently shifted from an ineife'ctive'position (FIGURES 1 and 3) to a position (FIG- URE 2) to dress the grinding sufrace of the wheel 14. When the dressing tool is in position to dress the grind wheel the wheel can be dressed by movement of the grinding means 13 in the same manner as it is moved to grind The base structure 11 is preferably formed of a metal casting comprising a rectangular panel or table 16 having a circumferential depending skirt 17. The base structure has four rubber pads 21 attached thereto by screws threaded in four fillets 23 on the underside of the panel 16 so that the base may conveniently rest on a bench or table top, not shown. The base panel 16 includes a downwardly extending tubular flange formation 24 which provides an opening 25 through the base to permit particles generated by the blade grinding operation to be discharged onto the surface on which the device rests. The bottom.

of the skirted panel 16 is closed, except underneath the opening 25, by a composition panel 28 which is secured to the bottom edges of the skirt 17 by the pads 21. The upper surface of the panel 16 has a triangular embossment 26 and a rectangular embossment 27 which form support surfaces for the knife holder 12 and the grinder means 13, respectively.

The knife holder 12 comprises a generally triangular support member 30 which has a flat bottom surface adapted to slide on the surface of the embossment 26. An upright member in the form of a wall 31 is formed integral with the support member at its broad end, and an abutment member or post structure 32 is formed integral with the support member at the narrow end thereof. The wall 31 has a V-notch 33 in the top edge for receiving the handle of the knife K, as shown in FIG. 1. The handle of the knife is secured in the notch by a clamp arm or member 34, one end of which is pivoted to the wall 31 and the opposite end of which may be urged downwardly against the knife handle by a screw nut 35 threaded on a bolt 36 which is pivoted on a pin extending between the sides of a slot 40' formed in one end of the wall 31. The left-hand end of the wall 31 projects upwardly between two parallel lugs 42, 43 which are downturned from the material forming the clamp arm 34, and the clamp arm is pivotally attached to the wall by a pivot pin 41. It will be apparent that the clamp bolt 36 can be swung about its pivot to be brought into and out of a slot 44 in the end of the arm 34 for clamping and releasing the arm 34 from engagement with the handle of the knife K.

The post 32 of the support member 30 carries a generally drum-shaped head 45 which has an axial shank 46 attached thereto journalled in -an opening through the post 32. The head 45 can be rotatably positioned by a knob 47 attached to the outer end of the shank 46. A dished spring washer 48 surrounds the shank 46 and is disposed between the knob 47 and the adjacent surface of post 32 to frictionally impede rotation of the shank and the head.

Two knife blade locating pins 50, 51 project from the side of the post 32 on which the head 45 is located and are spaced so that when the ring-like blade supporting and driving structure R of the knife K is in engagement with the two pins and flatly engaging the adjacent vertical wall of the post 32 the rotary blade B of the knife will be properly located in the knife supporting means. To facilitate location of the blade carryingportion of the knife .3 against the pins 50, 51, the head 45 carries a U-shaped spring member 52 which has its yoke portion suitably secured to a sloping surface 53 on the head 45. When the blade supporting portion R of the knife is positioned to surround the head 45 and engage the locating pins 50, 51, the head is rotated to bring the spring 52 to the position shown in FIG. 3 in which it engages the inner surface of the blade and urges the structure R against the pins. The clamp arm 34 is then clamped to the handle of the knife K to rigidly secure it in position. The head 45 can :be retained in either of its two positions shown in FIGURES 2 and 3 by a knurled headed lock screw 97 threaded into the post 32. The inner end of the screw 97 may engage in suitable apertures in the shaft-like part 46 of the head 45, which apertures are spaced 180 apart. It will be under st'ood that the diameter of the head 45 and its location is such that the spring 52 does not engage the blade supporting structure when the head is turned 90 or more from the position shown in FIG. 3. I

The knife holder support member 30 is guided for movement relative to the grinder wheel 14, as indicated by arrow 54, to bring the knife blade to a position tobe engaged by the grinder wheel. The guide means for this purpose comprises three bolts 55, 56, 57 which are attached to the bottom of the member and the shanks of which project through three slots 60, 61, 62 formed through the panel 16 so that the parallel edges of the slots guide the bolts in a straight line and limit the stroke through which the member moves.

The holder support member 30 can be accurately positioned relative to the grinder wheel by a fine adjusting screw 63 rotata'bly supported against axial movement in a bushing in a lug 64, formed on the panel 16 and extending upwardly therefrom, and threaded into an opening through the wall 31. A knurled knob 65 is attached to the outer end of the screw 64. The screw can be rotated to accurately position the knife holder 30 to cause the grinder wheel 14, when reciprocated, to lightly engage the knife blade B or the dressing tool 15 during grinding or dressing operations.

The knife holder support member 30 is urged or biased toward the outer edge of the base plate, that is, away from the path of movement of the blade grin-ding means, by a coil spring 66 having one end hooked to a pin 67 depending from the bottom side of panel 16 and the opposite end connected to the bolt 57. The spring 66 takes up any looseness between the adjusting screw 63 and the opening in which it, is threaded in the wall 31.

To facilitate lubrication of the sliding surfaces of the holder member 30 and the panel 16, an opening 68 is formed through the panel.

The blade grinding means 13 comprises an electric motor 70 having a driven shaft projecting from one end to which the grinder wheel 14 is attached. The motor 70 is supported on a pedestal 71 having a flat base plate 72 slidably supported on the top surface of the embossment 27 for reciprocal movement along a line which forms an angle with axis of the knife blade in the holder 12 corresponding to the angle of the outer beveled surface of the blade with the axis of the blade. To minimize friction of the base plate 70 on the embossment 27, ridges r runners 74 are formed on the bottom of the plate along opposite longitudinal edges and the engaging surfaces of the runners and embossment are preferably ground smooth.

The base plate 72 is guided in its reciprocable movement by four bolts 75, 76, 77, 78 which are attached to the underside of the base plate 72 adjacent the four respective corners thereof and extend through slots 80, 81, '82, 83, respectively, formed through the panel 16. The shanks of the bolts 75-78 engage the parallel sides of'the slots and thereby accurately guide the base plate 72 in a straight line and the ends of the slots limit the'travel of the base plate. The heads of the bolts 75-78 on the underside of the panel 16 prevent removal of the motor 70 from the base structure 11 but permit reciprocation thereof along the top of the base structure.

The motor 70 and its pedestal are reciprocated by a lever 84 pivoted on a pin 85 secured in a boss 86 formed on the panel 16, the lever having a forked end which receives an upwardly extending pin 87 between the tines thereof, the in being secured in the base plate 72. It will be apparent that oscillation of the lever 84 by the operator will cause the motor to be moved back and forth along the guide slots 80 83 to thereby move the grinder wheel 14 laterally along the beveled cutting edge of the circular knife.

The motor base plate 72 is urged toward the end of the guide slots remote from the knife holder by a coil spring 90, one end of which is hooked to a pin 91 depending from the, bottom of panel 16 and the other end of which is connected in an opening through a bar 92 interconnecting the two bolts 75, 77. The construction is such that the grinder wheel will be moved out of alignment with a blade in the holder 12 when the lever 84 is released.

The current supply for the motor 70 is furnished through a suitable flexible cord 94 which passes through openings in a skirt 17 and the base panel 16 and to the motor. A suitable control switch, not shown, is provided for controlling operation of the motor.

Grinding of the blade of the knife K is effected by securing the knife in the holder as described previously. The member 30 is then positioned along its guided path of movement by rotation of the knob 65 so that the grinder wheel 14 will lightly engage the outer beveled surface of the blade 8 as the motor 70 is reciprocated by oscillation of the lever 84. It will be understood that during the grinding operation the blade B is rotated about its axis by the driving mechanism of the knife which includes a flexible drive cable 99, connected with a motor, not shown, so that the entire periphery of the cutting edge of the blade B will be ground by the wheel 14.

It will be noted that the outer ends of the arms of the spring 52 are curved and the wide surfaces thereof are canted relative to the inner cylindrical surface of the blade B whereby the blade is engaged by the spring at point contacts only thereby minimizing friction between the rotating blade and the spring.

The grinder wheel 14 may be dressed by the dressing tool 15 by rotating the head 45 to position the tool to extend toward the line of movement of the periphery of the grinder wheel, as seen in FIG. 2, after which the knife holder member 30 is moved by rotation of the knob 65 to a position to which the dressing tool will lightly engage the grinder wheel 14 as the motor 70 and wheel are reciprocated by the lever 84 in the same manner as for sharpening knife blades. The dressing tool 15 is of conventional form, including a stem 95 which is inserted in a bore opening in a fiat side of the head, the stem being secured in place by a set screw 96. As already mentioned, the head 45 can be retained in either of its two positions shown in FIGS. 2 and 3 by a knurled headed lock screw 97 threaded into the post 32.

It will be'seen that the invention provides a portable device for quickly and accurately grinding the cutting blade of a rotary knife of the character referred to without removing it from the knife assembly and which device also provides for convenient, accurate and rapid dressing of the grinding wheel. I Although but one form of the invention has been shown, it is to be understood that other forms, modifications and adaptations could be made all falling within the scope of the claims which follow.

Having described my invention I claim: 1. In a sharpening device for a knife having a ringlike knife blade: a base, a knife holder supported on said base and including means to secure a knife with a ringlike blade in a predetermined location on the holder for contact with a sharpening wheel, and a rotable member carriedby said holder for engaging a part of a knife 'on the holder when the rotatable member is in one angular position; a knife blade sharpening wheel rotataby supported on said base, a sharpening wheel dressing tool attached to said rotatable member for engagement by said sharpening wheel when said head is in a different angular position, means for effecting relative movement between the knife holder and said sharpening wheel transversely of the axis of rotation of said sharpening wheel to thereby bring the knife blade and sharpening wheel into sharpening position relative to one another, and means for effecting relative movement between the knife holder and said sharpening wheel parallel to the axis of rotation of said sharpening wheel whereby said sharpening wheel is moved across a surface of a knife blade supported on the knife holder.

2. In a sharpening device for a knife having a ring-like knife blade: a base; a knife holder supported on the said base, said knife holder including an abutment for locating the blade at a fixed location on the holder and positioned to contact the knife outside the ring-like knife blade, and a'member spaced from the abutment movable into yielding engagement with the knife from within the ringlike knife blade to urge the knife against the abutment; a knife blade sharpening wheel rotatably supported on said base; and means for effecting relative movement between the knife holder and the sharpening wheel to sharpen a surface of a ring-like knife blade supported by the knife holder.

3. In a sharpening device for a knife havin a ring-like knife blade: a base; a knife holder supported on said base for movement to and from a knife sharpening position,

said knife holder including first, second and third spaced members for securing a knife with a handle and a ringlike blade in a predetermined location on the holder for contact with a sharpening wheel, the said first member including a recess and an adjustable clamp for receiving and securing the handle of a knife, the said second member being rotatable on the holder, adapted to fit within the ring-like blade, and including spring means for engaging the inside of the ring-like blade when the blade surrounds the second member and for urging the blade toward the third member, and the said third member being a locating abutment on the holder positioned to engage the knife outside the ring-like blade; and a knife blade sharpening wheel supported on the base for movement relative to the base along a surface of a blade supported in the knife holder.

References Cited UNITED STATES PATENTS 1,872,096 8/1932 Runshang 5196 1,875,547 9/1932 Anderson 51225 2,136,188 11/1938 Gagn 5195 2,827,657 3/1958 Bettcher 146203 X 3,114,989 12/1963 Allison 51105 3,279,126 10/1966 Barron 51-95 X LESTER M. SWINGLE, Primary Examiner.

D. G. KELLY, Assistant Examiner. 

